Transformer system provided with a decoupling system

ABSTRACT

To allow simple performance of a voltage test of a high-voltage system, a transformer system having a transformer housing ( 1 ) that receives a voltage converter ( 4 ) and having an electrical terminal ( 6 ) electrically connected to the voltage converter ( 4 ) and extended out of the transformer housing ( 1 ) for connecting the transformer system to a high- or medium-voltage system, is improved in that a decoupling system ( 12, 25 ) actuatable from outside the transformer housing ( 1 ) for temporarily interrupting the electrical connection between the voltage converter ( 4 ) and the first terminal ( 6 ) is disposed in the transformer housing ( 1 ). For performing a direct voltage test, the transformer system of the invention no longer has to be detached from the high-voltage system.

RELATED APPLICATIONS

This application is a 371 of PCT/EP98/05507 filed Aug. 29, 1998.

BACKGROUND OF THE INVENTION

The invention relates to a transformer system having a transformerhousing that receives a voltage converter and having an electricalterminal electrically connected to the voltage converter and extendedout of the transformer housing for connecting the transformer system toa high- or medium-voltage system.

Such transformer systems are known. For constant monitoring of the highvoltage, they are connected to high-voltage systems, such as switchingstations, and typically mounted solidly. For maintenance or testpurposes, however, the known transformer systems have to be detached.Particularly for a direct voltage cable test performed in thehigh-voltage system, an inductive voltage converter has to be removed;otherwise it would unavoidably be destroyed entirely when the test isperformed.

In many high-voltage systems with sockets for the connection ofhigh-voltage cables and voltage converters, the known transformer systemalso has to be detached for a different reason. Often there is no longerany unoccupied socket in the switching station to which a test cable fordelivering the direct voltage can be connected. The voltage convertermust then already be detached for that reason to allow the test cable tobe connected to the socket previously occupied by the voltage converter.

To perform the voltage test, the following steps are necessary in theknown systems:

The voltage converter is detached.

The socket that is now available is occupied by the test cable.

The direct voltage test is performed.

The test cable is detached.

The voltage converter is installed again.

Performing this procedure is time-consuming and expensive.

SUMMARY OF THE INVENTION

It is therefore the object of the present invention to disclose atransformer system of the type referred to at the outset with which avoltage test in a high-voltage system can be performed more simply.

This object is attained according to the invention in that a decouplingsystem actuatable from outside the transformer housing for temporarilyinterrupting the electrical connection between the voltage converter andthe first terminal is disposed in the transformer housing.

The transformer system of the invention permits the electricaldecoupling of the voltage converter from the high-voltage system withouthaving to detach anything. The direct voltage test can then be performedwithout destroying the voltage converter.

In a further feature of the invention, it is provided that a furtherelectrical terminal extended to the outside is provided, which isconnected to the first electrical terminal via a connection capable ofcarrying current. A test cable for the direct voltage supply can, againwithout detachment of the transformer system, be connected to thefurther electrical terminal extended to the outside. The connectioncapable of carrying current according to the invention reliably carriesthe test voltages or currents on to the first electrical terminalconnected to the high-voltage system.

If the first electrical terminal is embodied as a plug contact for beingplugged into a socket of a high-voltage system, and the furtherelectrical terminal is embodied as a socket, then the transformer systemof the invention can be connected in an especially simple way to thehigh-voltage system and the test cable. With a view to compatibility, itis especially expedient here if the bush and the plug contact areembodied as an inside cone in accordance with German Industrial StandardDIN 47637 or as an outside cone in accordance with DIN 47636.

A first embodiment of the invention provides that the insulation isembodied of cast resin; that the decoupling system has two contactsembedded in the cast resin and one hollow chamber, into which a bridgeelement serving the purpose of electrical connection of the contacts canbe inserted. Thus all the components can be embedded in the cast resinhousing in a single operation, and the voltage-carrying parts are alsoelectrically insulated in the same operation.

In a further feature of the invention, it is provided that the hollowchamber, accessible from outside through an introduction opening of thetransformer housing, is embodied conically and the bridge element isembodied in rod form; that the contacts are disposed on the axial endsof the hollow chamber; and that the bridge element can be introducedinto and retracted out of the conical hollow chamber axially through theintroduction opening. Because of its rod form, the bridge element can beinstalled in a simple way by being plugged axially into the conicalhollow chamber. In the process, it is guided by the conical form of thehollow chamber precisely to the rear contact, against which it has to bepressed.

If the introduction opening is embodied in the form of a bush,preferably in the form of a conventional high-voltage socket, inparticular in accordance with the aforementioned DIN standard, and isclosable by means of a cap, then for construction and manufacture astandardized shape that has already been used many times in othercontexts and has stood the test of time can be employed, which reducesconstruction and production costs.

The provision of a dummy cable plug disposed in the introduction openingbetween the bridge element (20) and the cap assures the conditions fortouch protection, because of the high-voltage strength of the dummycable plug.

The provision that on being inserted, the bridge element can be pressedagainst the first contact, disposed opposite the introduction opening,via an axially acting spring element assures simple and reliablecontacting as the bridge element is being plugged in.

If the second contact, disposed on the end of the hollow chamber towardthe introduction opening, is embodied as a contact ring, with a throughopening and axially acting contact element, then the bridge element canbe introduced without problems through the contact ring into the conicalhollow chamber. After that, a secure electrical contact is made by meansof the axially acting contact elements.

In a refinement of the invention, the hollow chamber, in the decoupledstate, can be provided not with the removed dummy cable plug and bridgeelement but instead with a special dummy plug of an elastic material,which fills up the hollow chamber and decouples the two contacts fromone another in a high-voltage-proof fashion. By this provision theinternal decoupling distance between the two contacts can be reduced toa minimum spacing because the elastic dummy plug presses flat againstthe inner surfaces of the hollow chamber and in particular against thecontact faces as well and in the process positively displaces the airout of the ac. This prevents sparkovers that could otherwise occurbetween the contacts in the air-filled hollow chamber. Along with thisprovision, however, the total dimensions of the transformer housing, itsweight, and the production costs are also reduced.

The invention can be improved still further by providing that the dummyplug is connected to a cap part that can be screwed instead of the capto the transformer housing. The dummy plug with a cap plug guaranteesthe conditions for touch protection, because of its high-voltagestrength.

Further advantages and details of the invention will become apparentfrom the ensuing description of exemplary embodiments in conjunctionwith the drawings.

BRIEF OF DESCRIPTION OF THE DRAWING

Individually, the drawings show:

FIG. 1, a first exemplary embodiment of a transformer system of theinvention in section;

FIG. 2, the same transformer system as in FIG. 1, in the decoupledstate;

FIG. 3, a second exemplary embodiment of a transformer system of theinvention, in section.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The transformer system of the invention shown in the drawings has atransformer housing 1 of cast resin 2 with a metal jacket 3. Aninductive voltage converter 4 is disposed in the transformer housing 1.

For electrically connecting the transformer system with ahigh-voltage-carrying socket, not shown, of a high-voltage system, aplug contact 6 which protrudes laterally past the transformer housing 1is provided as a first electrical terminal. The plug contact 6 comprisesan insulator part 7, a metal contact 8, and a conductor 9.

In the embodiment shown in FIG. 3, a socket 10, which is connected tothe conductor 9 of the plug contact 6 via a connection 11 capable ofcarrying current, is disposed on the side of the transformer housing 1opposite the plug contact 6.

In both embodiments, a decoupling system 12, which has two opposedcontacts 13, 14, is also disposed in the transformer housing 1. Thecontacts are each provided with field control electrodes 15, 16. Thefirst contact 13 is connected directly (FIGS. 1 and 2) or indirectly viaa connecting line 17 (FIG. 3) with the conductor 9 of the plug contact 6or with the connection 11 that is capable of carrying current. Thesecond contact 14 is connected to the other supply line 18 of thevoltage converter 4. A conical hollow chamber 19 is embodied between thetwo contacts 13, 14 and the cast resin 2, so that the contacts 13, 14are disposed on the axial ends of the hollow chamber 19. A rod-likebridge element 20 serving to connect the two contacts 13, 14electrically is disposed in the hollow chamber 19 and is embodied hereas a cylindrical conductor, but can also comprise a rod-shaped fuse.

The hollow chamber 19 of the decoupling system 12 is accessible fromoutside the transformer housing 1 via a introduction opening 21 embodiedas a conventional high-voltage socket. The introduction opening 21 canbe closed with a cap 22, which is screwed from outside onto thetransformer housing 1. Once the cap 22 has been taken off, the bridgeelement 20 can be axially introduced into the hollow chamber 19 orremoved through the introduction opening 21. After that, theintroduction opening 21 is provided with a dummy cable plug 41 enclosedwith the cap 22. Because of its high-voltage strength, the dummy cableplug 41 assures the conditions for touch protection.

Disposed between the first contact and the bridge element 20 is anaxially acting spring element 23, against which the bridge element 20 ispressed axially on being introduced into the hollow chamber 19. Thebridge element 20 is guided by the conical shape of the hollow chamber19 precisely onto the contact 13, and a secure electrical contacting isthus attained. The second contact 14 is embodied as a contact ring 24with a through opening, through which the bridge element 20 is thrust.In the final position, axially acting contact elements thus assure asecure electrical connection with the bridge element 20. The functionalstate is thus achieved.

For achieving the decoupled state, the dummy cable plug 41 is removedwhile the system is voltage-free, and the bridge element 20 is pulledout of the hollow chamber 19. After that, the hollow chamber is filledup by a special dummy plug 42 of an elastic material, preferablysilicon, which decouples the two contacts 13, 14 from one another (FIG.2) in high-voltage-proof fashion. The dummy plug 42 is connected to acap part 43, which is screwed instead of the cap 22 to the transformerhousing 1. Because the dummy plug 42 conforms closely to the contactfaces and the walls of the hollow chamber 19, the internal decouplingdistance between the two contacts 13, 14 can be reduced to a very muchlesser spacing than would be necessary if only air were located betweenthe contacts 13, 14. This also reduces the total dimensions, weight andproduction cost of the transformer housing 1. Because of itshigh-voltage strength, the dummy plug 42 with the cap part 43 assuresthe conditions for touch protection.

List of Reference Numerals

1 Transformer housing

2 Cast resin

3 Metal jacket

4 Voltage converter

6 Plug contact

7 Insulator part

8 Metal contact

9 Conductor

10 Socket

11 Connection

12 Decoupling system

13 First contact

14 Second contact

15 Field control electrode

16 Field control electrode

17 Connecting line

18 Supply line

19 Hollow chamber

20 Bridge element

21 Introduction opening

22 Cap

23 Spring element

24 Contact ring

41 Dummy cable plug

42 Cap part

What is claimed is:
 1. A transformer system, comprising a transformerhousing; a voltage converter received in said transformer housing; afirst electrical terminal electrically connected to said voltageconverter and extended out of said transformer housing for connection toa high-or medium-voltage system; a second electrical terminal extendedto an outside and connected to said electrical terminal via a currentcarrying connection; and a decoupling system disposed in saidtransformer housing and actuatable from outside of said transformerhousing for temporarily interrupting an electrical connection betweensaid voltage convertor and said first terminal.
 2. A transformer systemas defined in claim 1, wherein said first electrical terminal is formedas a plug contact for plugging into a socket of a high-voltage system,while said second electrical terminal is formed as a socket.
 3. Atransformer system, comprising a transformer housing; a voltageconvertor received in said transformer housing; a first electricalterminal electrically connected to said voltage convertor and extendedout of said transformer housing for connection to a high- ormedium-voltage system; a decoupling system disposed in said transformerhousing and actuatable from outside of said transformer housing fortemporarily interrupting an electrical connection between said voltageconvertor and said first terminal; and an insulation composed of castresin, said decoupling system having two contacts embodied in said castresin, a hollow chamber and a bridge element located in said hollowchamber for electrical connection of said contacts with one another. 4.A transformer system as defined in claim 3, wherein said transformerhousing has an introduction opening for making access to said hollowchamber, said hollow chamber being conical and said bridge element beingrod-shaped, said contacts being disposed on axial ends of said hollowchamber, said bridge element being introducible into and retractable outof said conical hollow chamber axially through said introductionopening.
 5. A transformer system as defined in claim 4, wherein saidintroduction opening is formed as a bush; and further comprising a capclosing said introduction opening.
 6. A transformer system as defined inclaim 5; and further comprising a dummy cable plug disposed in saidintroduction opening between said bridge element and said cap.
 7. Atransformer system as defined in claim 3; and further comprising anaxially acting spring element which presses said bridge element againstsaid first contact.
 8. A transformer system as defined in claim 4; andfurther comprising a second contact disposed on an end of said hollowchamber toward said introduction opening, said second contact beingformed as a contact ring with a through opening and an axially actingcontact element.
 9. A transformer system as defined in claim 3; andfurther comprising a dummy plug composed of an elastic material andfilling up said hollow chamber so as to decouple said contacts from oneanother.
 10. A transformer system as defined in claim 9; and furthercomprising a cap which closes said introduction opening, and screwed tosaid transformer housing, said dummy plug being connected to said cap.11. A transformer system, comprising a transformer housing; a voltageconverter received in said transformer housing, a first electricalterminal electrically connected to said voltage converter and extendedout of said transformer housing for connection to a high-ormedium-voltage system; a second electrical terminal extended to anoutside and connected to said electrical terminal via a current carryingconnection; a decoupling system disposed in said transformer housing andactuatable from outside of said transformer housing for temporarilyinterrupting an electrical connection between said voltage convertor andsaid first terminal; and an insulation composed of cast resin, saiddecoupling system having two contacts embodied in said cast resin, ahollow chamber and a bridge element located in said one hollow chamberfor electrical connection of said contacts with one another.